My main complaint is the MDI. I don't think non-native widgets are a problem as long as they're done well and behave close enough to native widgets as to not confuse people.
Qt is probably the best example of this, so much that people will actually cite it as an example of a native UI toolkit when in fact it isn't, it just skins its widgets to look like it.
Qt is probably the best example of this, so much that people will actually cite it as an example of a native UI toolkit when in fact it isn't, it just skins its widgets to look like it.